The lsm-pf-v4.so and lsm-pf-v6.so
shared objects are the modules that handle IP filtering and NAT (Network
Address Translation) services.
You need to load these libraries to enable filtering and NAT functionality.

IP filtering allows your host to act as a firewall, or you can provide
firewall services on your host.
NAT allows multiple hosts on a subnet to share a common IP address.

You use configuration files to set the filtering and NAT rules.
For more details, see the documentation for
pf.conf.